The present invention relates generally to an apparatus for detecting gas entrapped in a liquid lubricating system, and more specifically, to an aeration sensing device for detecting gas entrapped in the engine oil of an internal combustion engine.
Engine oil has been used in engine systems to lubricate moving parts such as pistons, piston rods, compression rings, and other engine components to reduce friction and heat build up between the moving parts and an engine block. Contaminants or foreign substances found in the engine oil can inherently damage an engine system. Gas, such as air or combustion products, entrapped in the lubricant can also result in improper or inadequate lubrication of the engine components and can damage engine components including the oil pump.
Vehicle systems utilize various sensors within a vehicle to monitor whether an engine is operating within normal operating parameters. One type of such sensors is an oil pressure sensor that monitors the oil pressure exiting from the oil pump. If the oil pressure goes below or above a predetermined operating range, a warning indicator is displayed to the operator of a vehicle informing the operator of the improper operating condition that is occurring. However, oil pressure sensors are used only for detecting the oil pressure of the engine system, and such sensors are not indicative of aeration caused by gas entrapped in the engine oil. Aeration within the engine oil may not necessarily affect the oil pressure, but the aeration could still cause damage to the engine components. An aeration detection system as described in U.S. Pat. No. 4,599,888 utilizes a rod encased within a cylinder for monitoring the capacitance with oil flowing between the rod and the cylinder wall. However, other impurities or contaminants within the engine oil could change the capacitance. The system in the referenced patent does not differentiate between contaminants in the lubricant causing a capacitance change and aeration in the system causing a capacitance change.